A driver may transfer information with specific meanings to other vehicles through lights and whistles etc. of his/her vehicle while driving. For example, turn-on of high beams is one of the important causes of traffic accidents during driving at night, and in order to reduce dangers caused by the high beams for driving at night, a driver may alert a driver of an oncoming vehicle of which a high beam is turned on to turn off the high beam by alternately turning on a high beam and a low beam. However, this alert manner has a weak degree of alert, and it is often impossible to effectively alert the driver of the oncoming vehicle to turn off the high beam thereof, and thus it is difficult to reduce the occurrence of accidents.